Method and instrument for sensing fatigue, shock and/or acute stress

ABSTRACT

An instrument for sensing fatigue, includes a first temperature sensor for measuring a first temperature at a hottest spot of an uncovered part of a person&#39;s body; a second temperature sensor for measuring a second temperature at a coldest spot of an uncovered part of a person&#39;s body; and a comparator connected to the first and second temperature sensors for generating a temperature signal representing a temperature difference between the first and second temperatures.

FIELD OF THE INVENTION

The subject of the invention is a method for controlling the progress offatigue of a person doing some kind of a tiring activity and for theprevention of the effects of fatigue. Subject of the invention isfurther an instrument for sensing fatigue, states of shock and/or acutestress, completed with a device for evaluating the temperatures on thesurface of parts of the body.

An activity most typically tiring, the breaking off of which usuallydepends not on the state of fatigue but on other factors (e.g. arrivingat the destination, end of shift, etc.), is driving a car.

It is known that most people become alert and active when startingdriving, which, among other things, manifests itself in an increasedstimulus of motion and speech. After several hours of driving, driversgrow more irritable, their movements get slower and their way of drivingbecomes more careless. It is provable that pending on the distance andthe time of driving, a temporary vascular stenosis appears, mainly inthe small blood vessels of the drivers. People in this state more oftenhave accidents, that is why it is important to recognize and prevent orcancel this condition. It is also known that the states of shock andacute stress primarily appear in the form of the constriction of thesmall vessels.

DESCRIPTION OF THE PRIOR ART

There exists a diagnostic method (Hungarian patent of the Inventor No.191 121) capable of examining people (expediently drivers) exposed tostress, which is based on the statistical processing of the changes inthermograms of the face, and the purpose of which is to detect andmeasure the tolerance of drivers and the damages coming from theiroccupation. According to the procedure, thermograms--pictures of theinfrared radiation--of the face and hands of the person to examine aremade before the stress is to appear. The differences in the variousparts of the thermograms are recorded in a quantitative way, on thebasis of the dominant isotherms,

The patients can be examined again after the stress influence, dependingon the aim of the examination.

There is not known any applicable method based on the above principle todetect the process of fatigue, because it is too complicated andtime-taking.

There is a treatment for fatigue by means of an instrument (EP 0 209 246A1) generating electromagnetic fields mounted on the back of thedriver's seat. It consists of the flat coil on the back of the seat andan impulse generator connected to it. The impulse generator produces 5impulses 5 msec long each with 15 msec long pauses, repeating this for30 minutes with 100 msec pauses every four hours.

The flux density induced in the coil is 50 Gauss of which a flux densityof 15 Gauss falls on the body surface. According to the description, theinstrument is good for the relaxation of the drivers muscles.

Whereas this instrument is suitable for relieving the fatigue ofdrivers, the way of application outlined in the description, the lengthand repetition of the treatment do not agree with the regeneration needsof the driver as the exposure is less frequent and much longer than itwould be the best for him.

SUMMARY OF THE INVENTION

Aim of the invention is to develop a method and instrument to controlfatigue, making it possible to perform the treatment in the course ofthe fatiguing activity at the optimum time, and depending on the degreeof fatigue.

Basis of the invention is the recognition that the drop of thetemperature of the acrons--i.e. the free surfaces of the human bodywoven through with small blood vessels--, compared to the innertemperature of the body is characteristic of the state of fatigue.Furthermore it is satisfactory to watch the temperature fluctuation ofone such surface point to draw conslusions. It is serviceable to choosethe auricle as a surface point.

The solution of the task according to the invention is a procedure tocontrol the process of fatigue of a person displaying a tiring activity,and the prevention of the effects of fatigue. First, the temperatures ofthe to estimated coldest and hottest spots on the head of the personstill in a state of rest are taken. Then, in the course of his activity,temperature measurement is carried out from time to time orcontinuously, on the same--either the coldest or the hottest and thecoldest--spots of the head. Then the difference of the relatedtemperature data of the hottest and the coldest spots are taken, and thechanges in the temperature differences are watched. When the change ofthe temperature difference exceeds a certain value, the person is warnedof his state of fatigue and/or a fatigue-reducing treatment isadministered.

It is advantageous to take the temperature of the inner canthus as thehottest spot on the head.

It is to the purpose to take the temperature of the upper part of theauricle as the coldest spot on the head.

It is advantageous to handle the temperature of the hottest spot on thehead as an experimentally defined average or once-measured constantvalue.

It is to the purpose to apply a treatment of pulsing electro-magneticfield for reducing fatigue.

It is advantageous to administer the pulsing electro-magnetic treatmentduring the tiring activity.

It is to the purpose to go on with measuring the temperature during thefatigue-reducing treatment or refreshing of the driver and to stop thetreatment when the difference of temperature reaches or approximates thevalue of the state of rest.

An instrument detecting fatigue, states of shock and/or acute stress isalso a part of the invention, with a device evaluating temperatures onthe surface of the parts of the body. That device has a memory for theconstant values of the temperatures taken at the approx. hottest free(uncovered) spots on the surface of the parts of the body; or atemperature sensing capacity for measuring temperature data; also atemperature sensing capacity for measuring the temperature data of therelatively coldest spot of uncovered parts of the body, which areconnected to the input of the device defining the temperaturedifferences.

It is advantageous to fix the temperature sensor taking the temperatureof the relatively coldest spot on the temple or the bridge ofspectacles.

It is to the purpose to fix the temperature sensor taking thetemperature of the inner canthus, too, on the spectacle-frame.

It is advantageous if the fatigue-sensing instrument has a limit valuememory and a comparator.

It is to the purpose if the fatigue-sensing instrument has asound-signal unit.

It is advantageous if the fatigue-sensing instrument is connected to aseat for pulsing electro-magnetic field treatment.

The advantage of the solution according the invention is that it makespossible the regular or continuous evaluation of the degree of fatigueof the person, without stopping his activity; the intervention at theoptimum time; and the measuring of the effect of the fatigue-reducingtreatment. The fatigue-sensing instrument is capable of accomplishingthe method according to the invention; can be easily fixed on theexamined person; does not disturb work; makes it possible to measure thedegree of fatigue without disturbing work; and gives warnings to theperson growing more tired.

The invention is also suitable for detecting and cancelling conditionsthat go together with the stenosis of the small vessels, the so calledend arterioles.

Conditions like this are e.g. heavy stress influences and states ofshock. This phenomenon first appears at the apices of the humanorganism, the so called acrons, thus at the tip of the nose and in theauricle.

The effect of the consumption of a small quantity of alcohol, in thebeginning, is the dilatation of the blood vessels in question. The statebrought about by the influence of alcohol is divided to differentstages. Driving is highly worsened in the state when the stage ofvasodilatation is followed by the vascular stenosis in the skin. Theseare the second and third stages. The flushed face gets pale. Thiscondition again starts with the narrowing of the blood vessels in thenose and the external ear. Because of the vasoconstriction, these areassuddenly cool down.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter the invention is going to be outlined relying on an exampleof effectuation.

The method according to the invention is carried out on a bus driver.

In the course of the procedure, the face of the bus driver is examinedperiodically or continuously and the signs of fatigue caused by drivingare evaluated. In the evaluation, the temperature of the inner canthusis compared with the temperature of the coldest spot in the face(expediently the nose), and the changes of the temperature differenceare processed. The sign of tiredness is that the temperature of the nosedecreases, thus the temperature difference between the canthus and thenose grows.

On perception of the sign of tiredness--suitably in the case of aheavier fatigue, defined by the length of time since the perception--thedriver is given a pulsing electro-magnetic field treatment.

The parameters of the pulsing electro-magnetic (magnetic) field are asfollows:

    ______________________________________                                        magnetic induction:     8 mT                                                  impulse repetition frequency:                                                                         5 Hz                                                  impulse space factor:   25%                                                   length of pulse groups: 100 msec                                              interval between pulse groups:                                                                        100 msec.                                             ______________________________________                                    

It has to be noted that the influence of the pulsing electro-magneticfield can be different depending on the pulse frequency: slower impulses(e.g. 2 pulse/sec) quicken the metabolism, while faster ones. (e.g. 50pulse/sec) reduce it. In such a way, therefore, the relaxation ortenseness of the muscles, the dilatation or constriction of the bloodvessels can be achieved as well.

By the help of the treatment, in a few minutes, the driver's small bloodvessels that are narrowed because of his tiredness will dilate, whichimproves his blood supply in the face, and as a result, the signs offatigue disappear from the face, and the nose and other cold spots ofthe face warm up. Continuously measuring the temperature of the coldestspot in the face during the refreshing treatment, we shall getinformation on the loosening of fatigue and the treatment can befinished. 1-20 minutes of treatment will give the best results, as in aperiod as long as that all muscles get relaxed.

The procedure can be carried out en route or at a stop (e.g. at theterminal station of a city line), but it is essential to accomplish thereference examination when the driver is still in a state of rest.

The examination can be performed by means of a monitor, by comparing theimages displaying the temperature differences on the monitor, or in thecomputer processing unit. The evaluation is simplified by the fact thatit is not necessary to process all the temperature changes of the facebut it is enough to compare the temperature differences measured at thestates of rest and fatigue at the hottest and the coldest spots of theface.

Starting and stopping the pulsing electro-magnetic field treatment canbe done manually but automatically as well, when it is independent fromthe driver's will.

The results of the evaluation are recorded. Taking the mean values ofthe recorded date, the optimum length of the treatment anddistance--covering which it is reasonable to carry out the treatment forall drivers--can be defined.

An instrument sensing fatigue can be advantageously used for thedetection of the temperature difference between the inner canthus andthe coldest spot of the face (the acrons--the tip of the nose--theauricle, etc.), with an infrared sensor directed to the inner canthus ora contact thermometer fixed on the bridge of a pair of spectacles. Thereis a similar thermometer built in the spectacle frame. It is either on acomplement above the tip of the nose or on the temples of the frame,directed to the upper edge of the auricle. There is also a dataprocessing electronic circuit in the temples of the frame and aninfrared marker in the bridge. This latter one is partly to inform theperson wearing the spectacles about the critical degree of his fatigueand partly to cooperate with the infrared receiver unit on thedashboard, starting and stopping the electro-magnetic treatment,controlled by the temperature difference. The fatigue sensing instrumentincludes a memory or a temperature sensor for the constant temperaturevalue of the relatively hottest spot on the uncovered part of the body;and a temperature sensor for the relatively coldest surface of theuncovered part of the body, that are all connected to the input of adifferential device. The differential device is fitted with anotherdifferential device that compares the momentary temperature differencewith the temperature difference characteristic of the state of rest. Toits output a comparator is connected that compares the difference valuewith the permissible value. The infraredmarker is connected to thecomparator output.

The advantage of the fatigue sensing spectacles over a video camera isthat temperature sensing only takes place at two constant points, thusit becomes needless to select the useful measurement data from among asuperfluous set of data. The instrument made for this procedure is muchsimpler, less expensive and does not take a lot of room in the driver'scabin.

The degree of fatigue that demands intervention can be displayed by afatigue sensing ear thermometer too. It can be fixed on the ear or thetemple of the spectacles. When the driver puts it on its temperaturesensing contact unit touches the back side of the auricle. It alsoincludes a memory that stores the permissible value proportional to thetemperature of the inner canthus; a circuit that compares thetemperature taken by the contact unit to the value in the permissiblevalue memory; and a sound signal to sign that the actual temperaturetaken by the contact unit sank below the permissible value.

The fatigue sensing instrument in the example is built in a spectacleframe.

On the spectacle there are further temperature sensors for measuring thetemperatures of the inner canthus and one of the coldest spots (theauricle or the tip of the nose) on the head. The latter one is eitherfixed on the temple of the spectacle frame and directed to the upperedge of the auricle or on the bridge of the frame and directed to thetip of the nose. The two temperature sensors are electronicallyconnected to a differential device. At its output a sign is displayedcorresponding to the difference of the temperatures taken by the twotemperature sensors at the same time. The temperature difference iscompared to the one belonging to the state of rest. When the differencebetween the two temperature differences exceeds a permitted value (e.g.4 degrees centigrade), the examined person is warned or given arefreshing treatment.

In a simple version of the construction the fastening part is a hookthat can be affixed to the ear. The memory for the permitted value iseither connected to the thermometer measuring the temperature of theinner canthus or it is sotred in the memory as a constant value that isalready known. It is suitable if the signal is a buzzing sound whichsounds depending on the comparison of the momentary temperaturedifferences to a permitted value.

It is practical if the permitted value in this case is 32 degreescentigrade. In practice the display remains true enough in thetemperature range good for driving (15-50 degrees centigrade) even ifthe permitted value is taken as constant.

Displays in different temperature ranges make it possible to adapt theinstrument, i.e. the display system for detecting states of preshock orstress conditions dangerous for the organism or conditions of unfitnessfor driving (because of the effect of alcohol). To cancel theseconditions, the pulsing electro-magnetic treatment is only partlysuitable. That is why it is only the signalling of a dangerous conditionthat is important concerning the invention.

I claim:
 1. A method of monitoring fatigue of a person performing atiring activity and of preventing effects of fatigue, comprising thefollowing steps:(a) while the person is at rest prior to performing theactivity, taking a first temperature at a hottest spot and a secondtemperature at a coldest spot of the person's head; (b) repeatedlytaking said first and second temperatures during the activity; (c)calculating a temperature difference between said first and secondtemperatures; (d) monitoring a change of said temperature differenceduring the activity; (e) generating a signal when said temperaturedifference exceeds a predetermined value.
 2. The method as defined inclaim 1, wherein step (b) is performed intermittently.
 3. The method asdefined in claim 1, wherein step (b) is performed continuously.
 4. Themethod as defined in claim 1, further comprising the step of triggeringa warning by the signal generated in step (e).
 5. The method as definedin claim 1, wherein steps (a) and (b) comprise the step of taking saidsecond temperature at the upper edge of the auricle.
 6. The method asdefined in claim 1, wherein steps (a) and (b) comprise the step oftaking said first temperature at the inner canthus.
 7. The method asdefined in claim l, further comprising the step of triggering, by thesignal generated in step (e), a refreshing treatment administered to theperson.
 8. The method as defined in claim 7, comprising the steps ofperforming steps (b), (c) and (d) during performance of said refreshingtreatment on the person at rest and discontinuing said treatment whensaid temperature difference at least approximates the temperaturedifference between the temperatures obtained in step (a).
 9. The methodas defined in claim 7, wherein said refreshing treatment comprises thestep of applying a pulsing electromagnetic field.
 10. The method asdefined in claim 9, wherein said step of applying a pulsingelectromagnetic field is performed during said activity.
 11. A method ofmonitoring fatigue of a person performing a tiring activity and ofpreventing effects of fatigue, comprising the following steps:(a) takinga first temperature at a hottest spot of the person's head; (b) whilethe person is at rest prior to performing the activity, taking a secondtemperature at a coldest spot of the person's head; (b) repeatedlytaking said second temperature during the activity; (c) calculating atemperature difference between said first and second temperatures; (d)monitoring a change of said temperature difference during the activity;(e) generating a signal when said temperature difference exceeds apredetermined value.
 12. The method as defined in claim 11, wherein step(a) comprises the step of repeatedly taking said first temperature andfurther comprising the step of calculating an average of the firsttemperatures.
 13. The method as defined in claim 11, wherein step (a)comprises the step of taking said first temperature once.
 14. Aninstrument for sensing fatigue, comprisising:(a) a memory containingdata representing a first, constant temperature of a relatively hottestspot an uncovered part of a person's body; (b) a temperature sensor formeasuring a second temperature at a relatively coldest spot of anuncovered part of a person's body; and (c) comparator means connected tosaid memory said temperature sensor for generating a temperature signalrepresenting a temperature difference between said first and secondtemperatures.
 15. A combination of an instrument for sensing fatiguewith a spectacle frame; comprising(a) a temple part comprised in saidspectacle frame; (b) a bridge part comprised in said spectacle frame;(c) a first temperature sensor for measuring a first temperature at ahottest spot of a person's head; (d) a second temperature sensor formeasuring a second temperature at a coldest spot of the person's head;said second temperature sensor being mounted on one of said parts of thespectacle frame; and (e) comparator means connected said first andsecond temperature sensors for generating a temperature signalrepresenting a temperature difference between said first and secondtemperatures.
 16. A combination of an instrument for sensing fatiguewith a spectacle frame; comprising(a) a first temperature sensor formeasuring a first temperature at a hottest spot of a person's head; saidfirst temperature sensor being mounted on said spectacle frame formeasuring the temperature of the inner canthus; (b) a second temperaturesensor for measuring a second temperature at a coldest spot of theperson's head; and (c) comparator means connected to said first andsecond temperature sensors for generating a temperature signalrepresenting a temperature difference between said first and secondtemperatures.